Conventional self-curing endodontic sealant composites use peroxide, mostly benzoyl peroxide (BPO) as the oxidant part of the redox initiator system. This system, consisting of BPO, in combination with a tertiary amine such as bis(2-hydroxyl)-p-toluidine (DHEPT), and dimethyl-p-toluidine (DMPT) as a reducing agent, can have sufficient curing time at room temperature. But BPO has a low half-life, resulting in poor shelf-life stability. Pastes containing BPO harden readily when stored at elevated temperatures. The self-curing of other peroxides with longer half-life, such as cumyl peroxide, t-butyl peroxide, initiated by an amine, is too slow to give a sufficiently rapid curing rate for acrylate resins.
Compositions based on polymerizable methacrylate monomers can be polymerized using hydroperoxide/thiourea redox systems, such as in U.S. Pat. No. 3,991,008 directed to dental compositions having improved color stability; U.S. Pat. No. 4,569,976 directed to a redox cure system for acrylic adhesive compositions; and U.S. Pat. No. 3,970,505 directed to anaerobic compositions and a surface activator therefore, all of which have hereby incorporated by reference.
These patents have not reported any stabilized paste formulations for the use in endodontic compositions. The studies were limited to room temperature conditions and no self-curing paste formulations at elevated temperatures of up to 60° C. were reported in any field.
It is desirable to provide a stable self-curing endodontic composition having a sufficient curing rate. It would be beneficial to provide an endodontic sealing composition having stable shelf life at high temperatures.